Stepdad chiming in…
2 stepsons, 14 years old, 17 years old.
only major difference was that she was widowed and not divorced, the boys were babies when he died.
My beautiful wife had herself talked into being the doormat for her son. “You always put your children first” She was taught. What the sons learned was that mom gets last place and no respect because she jumped whenever they yelled her name.
So…
You’re real problem is not your stepson, the real problem is/will be your relationship with your wife. Your stepson does not even live with you full time, for crying out loud. You and your wife would both benefit with some counselling, however brief, she might need to learn to let go of her desire to control her son (trust me, it’s a control issue). She will need to “let go” and allow him to set his own limits, and not go somewhere if he doesn’t want to go.
You, my friend, need to learn to stand up to the plate and say something like: “You are 16 years old, since it would be wrong, and illegal to punch you in the mouth for what you just said to my wife, I will give you this final warning, any more disrespect will result in me dragging you into the car and taking you back home to daddy’s house where you will, no doubt, be much happier”
You have a chance to be mentor, or at least a good example. Believe me, he’s watching everything you say and do. Besides, it’s your house, you do not have to put up with that crap. He’s not a little boy, he’ll survive if he’s dropped off on the porch of the house where he lives even if daddy’s not home. If he won’t get into the car, tell him to start walking and kick him out of the house. Point him in the direction of the nearest bus stop. Do all of this politely but firmly.
The biggest problem some teenage boys have is that they are far too shielded from the consequences of their behavior.
If all else fails tell him that according to the rules of the house there is no rule #6! (obligatory Monty Python reference.)
Hang in there.